By default, the Kendo UI Grid for ASP.NET MVC makes POST requests when configured for Ajax binding. This is implemented by a custom DataSource transport and schema. Those are defined in the kendo.aspnetmvc.min.js.

Check the Network—or Net in Firebug—tab of the browser developer console. Look for a failed HTTP request for the action method configured via the DataSource Grid setting.

HTTP status code 401 indicates that the required authentication has failed or has not been provided yet.

HTTP status code 403 indicates that the request is not authorized. Perhaps the current user does not have the required permissions.

HTTP status code 404 indicates that the requested URL cannot be found. Check if the controller and action names are spelled correctly.

HTTP status code 500 indicates that a server error occurred while processing the request. Check what the server response is. In most cases, it will contain the full .NET stacktrace. If the reason for the exception is not clear, put a break-point in the action method and break with the debugger. Also, refer to the article on well-known exceptions.

Check if you are using the ToDataSourceResult extension method. That method returns the data in the JSON format expected by the Kendo UI Grid. For further instructions, refer to the article on Grid Ajax binding.